The present invention relates to a method for preparing fluorescent polymers, and coating compositions containing such fluorescent polymers. In particular, the present method relates to the inclusion of fluorescent compounds in the preparation of polymers useful in coating compositions such that the resultant compositions are detectable by fluorescent means.
A method for preparing a fluorescent polymer is disclosed in U.S. Pat. No. 5,125,929 (Amey). There, a Michael addition reaction produces a linear aminoacid polymer which is fluorescent. In this case, the fluorescence is produced by the polymer backbone. This method is limited by the nature of its chemistry. Moreover, most polymers produced by a Michael addition reaction will not have fluorescence.
U.S. Pat. No. 5,043,406 (Fong) discloses a method for incorporating fluorescent moieties into acrylamide polymers by copolymerizing acrylamide monomers with monomers containing pendant fluorescent moieties. The principal limitation to this method is the lack of commercially available monomers containing pendant fluorescent moieties. Even if other monomers could be modified to incorporate pendant fluorescent moieties, the increased cost of doing so would make the cost of such fluorescent polymers prohibitive.
Both the methods described by Amey and Fong are limited in applicability, either by virtue of the nature of the chemistry involved, or by the lack of available fluorescent starting materials. What is needed is a method for incorporating fluorescence into a broad variety of polymers, thus permitting broader usage of such fluorescent polymers.